NAME

LucyX::Search::Filter - Build a caching filter based on results of a Query.

SYNOPSIS

    my %category_filters;
    for my $category (qw( sweet sour salty bitter )) {
        my $cat_query = Lucy::Search::TermQuery->new(
            field => 'category',
            term  => $category,
        );
        $category_filters{$category} = LucyX::Search::Filter->new( 
            query => $cat_query, 
        );
    }
    
    while ( my $cgi = CGI::Fast->new ) {
        my $user_query = $cgi->param('q');
        my $filter     = $category_filters{ $cgi->param('category') };
        my $and_query  = Lucy::Search::ANDQuery->new;
        $and_query->add_child($user_query);
        $and_query->add_child($filter);
        my $hits = $searcher->hits( query => $and_query );
        ...

DESCRIPTION

A Filter is a Lucy::Search::Query subclass that can be used to filter the results of another Query. The effect is very similar to simply using the wrapped inner query, but there are two important differences:

A Filter does not contribute to the score of the documents it matches.
A Filter caches its results, so it is more efficient if you use it more than once.

To obtain logically equivalent results to the Filter but avoid the caching, substitute the wrapped query but use set_boost() to set its boost to 0.

METHODS

new

    my $filter = LucyX::Search::Filter->new(
        query => $query;
    );

Constructor. Takes one hash-style parameter, query, which must be an object belonging to a subclass of Lucy::Search::Query.

BUGS

Filters do not cache when used in a search cluster with LucyX::Remote's SearchServer and SearchClient.